So, yesterday I was chatting with my daughter. She was talking with her team and for some reason one of them pulled out an interview question from their company's question bank. Turns out it was today's Advent of Code problem. As with past years, I'm going to try to solve the problems in Clojure but if I can will talk Python when I talk about solutions. Part 1 of the problem basically asks for you to find a pair of numbers in an array that sum to a specific value.

Tomorrow, or more practically, tonight at Midnight, Eric Wastl will once again launch the Advent of Code. As I've written before, it's a month long event where each day a new programming problem is released. The problems range in difficulty and complexity. Some are very approachable to beginners and some are crazy challenging. I've written a bunch about AOC in past years: Solve A to Solve B Data structures and Hidden Complexity Tools can shape- how we think 2019 day 1 2019 day 2 2019 day 3 2019 day 4 2019 day 8 2019 day 8 addendum and a few more not listed.

In the real world you're usually not building your own projects from scratch. Much more frequently you're working on a team and you and other players come and go over time. This is in stark contrast to most CS educational experiences where students typically complete relatively small assignments from beginning to end. One of my biggest fears way back when as I was about to graduate college was when I woke up one night in a cold sweath "oh crap - in a couple of weeks I'm going to have to actually produce good code.

As I said in my last post, day 8 would be a nice project or lesson in an APCS-A or college CS1 class. Another nice problem would be to write a program to generate an image in the format required by the question. Alternatively, a teacher doing day 8 with their classes might want to generate a bunch of images for the students to test their decoders on. I thought I'd write one to see how appropriate it would be for the students.

I spent most of last week up in Albany working on the NY State K12 CS Standards so fell a bit behind. I had to go back to complete day 5 but still haven't finished day 7 which builds on day 5 which in turn builds on day 2. I might not get to finishing 7 for a while but it looks like a good chance to play with core.

Day 4. Most of the day was spent working on the NY State CS standards to I didn't figure to have much time to work on the problem. Fortunately, I was able to knock out part 1 before work started and part 2 was a quick adjustment when I got back to it at the start of lunch. Once again, it was a problem with a few interesting teacher side aspects.

Today's problem dealt with intersecting paths. You start with two inputs, figure out the paths they represent and where they intersect and then find the intersection that correctly answers the question. For part 1 you have to find the intersection closest to the origin. From a teacher's point of view, the interesting part here is data representation. This problem deals with a two dimensional grid on which the paths live.

Day 2 of Advent of Code 2019 was also pretty straightforward and once again I wrote my solution in Clojure but in order to talk about this from a teacher's point of view, we'll look at a Python solution. At its core, this is a simulation problem - read the data into an array or list and write a program to run through the steps. At first I was hoping that the solution would consume the data - that is, once you read past an instruction you don't go back to it.

Like most programming challenges, Advent of Code ramps out from easier, more accessible problems to harder, more complex ones. As such, a number of the early challenges are great problems for early CS students. I thought that while I watched my NY Giants play valiantly in their attempt to get a high draft pick I'd talk about today's challenge from a teacher's point of view. The summary of part one is that you have a list of inputs (masses of components) and for each one you have to perform a calculation (how much fuel is needed).